Laser-based system for material deposition and removal

Abstract

A laser-based repair system provides for material removal and deposition using a repair tool having a first laser operating at a high power for cutting signal lines and operating at a lower power for ablating a target repair area in conjunction with a liquid dispensing apparatus for application of the liquid solution in a target area, and a second laser for decomposing the liquid solution in an applied layer prior to the ablation of material in the target repair area. Various repair processes can be undertaken. The invention allows high-speed material deposition and removal on a surface. In a specific embodiment of the invention, the liquid solution used is a palladium acetate and a solvent or other metallo-organic solution which is capable of pyrolytic reaction and decomposition to an electrically conductive residue. A liquid applicator or dispensing apparatus is provided which is suited to applying fine traces of liquid without clogging. An optical head is provided which project beams from a plurality of lasers and surface illumination along a common axis with an optical viewing system for lighting a target workpiece for observing the repair in progress. The invention is particularly useful in the repair of large matrices, such as liquid crystal display panels.

What is claimed is: 
     
       1. A laser repair system for microcircuit repair by material deposition and removal comprising: a) a first laser for cutting and ablating target areas in a workpiece;   b) a dispensing means for applying a metallo-organic liquid solution to said target areas;   c) a second laser for decomposing said liquid solution to a conductive metal including in said target areas;   d) an optical means for combining beams of said first laser and said second laser along a common axis; and   e) a workpiece placement means for moving said workpiece.   
     
     
       2. The laser repair system as recited in claim 1 wherein said first laser is an excimer laser. 
     
     
       3. The laser repair system as recited in claim 1 wherein said second laser is an argon-ion laser. 
     
     
       4. The laser repair system as recited in claim 1 wherein said dispensing means includes means for establishing an air bearing for maintaining a controlled distance between said dispensing means and said workpiece so that said dispensing means avoids contact with said workpiece. 
     
     
       5. The laser repair system as recited in claim 4 wherein said dispensing means has a bearing face and includes an air outlet and a liquid solution outlet in said bearing face. 
     
     
       6. The laser repair system as recited in claim 5 wherein the bearing face forms a doctor blade for shearing said liquid solution. 
     
     
       7. The laser repair system as recited in claim 1 further comprising a viewing system in said optical means for observing said workpiece. 
     
     
       8. The laser repair system as recited in claim 7 wherein said optical means includes means for illuminating said workpiece and for observing said workpiece along said common axis with said laser beams. 
     
     
       9. The laser repair system as recited in claim 1 further including heating elements placed in said workpiece placement means for accelerating drying time of said workpiece. 
     
     
       10. The laser repair system as recited in claim 1 further including means for shaping the beam of said first laser and the beam of said second laser into top hat-shaped intensity cross sections. 
     
     
       11. A method for opening a via in a passivation layer having an interface upon a metal layer of a circuit structure constructed upon a substrate in order to expose said metal layer to allow contact of a signal conduction overlay with said metal layer, said method comprising the steps of: a) generating a beam in pulses from an excimer laser with sufficient energy such that upon injection of at least one pulse of said beam into said passivation layer said interface upon said metal layer will break down;   b) shaping said beam to define a cross-sectional area with substantially constant intensity and sharp boundaries in the form of a top hat;   c) injecting said top hat-shaped beam into said passivation layer at a target area for a sufficient duration and a sufficient number of times to cause said interface to break down; and   d) removing said passivation layer in the target area to define said via.   
     
     
       12. The method according to claim 11 wherein said removing step comprises: vaporizing said passivation layer in said target area with said top hat-shaped beam.   
     
     
       13. The method according to claim 11 wherein said removing step comprises: exploding said interface between said conduction layer and said passivation layer in said target area to leaving an unconnected residue of said passivation layer; and   extricating said unconnected residue from said passivation layer.   
     
     
       14. The method according to claim 13 wherein said extricating step comprises: vacuuming said unconnected residue from said passivation layer.   
     
     
       15. The method according to claim 13 wherein said extricating step comprises: blowing away said unconnected residue from said passivation layer.